Powertrain - CI/ SI Engine Model

I need to create the model of a SI engine of a FSAE vehicle, but the data I have fit better in the simulink model of your SI engine (I have the fuel rate as output that is taken in input from the CI engine model but not from the SI model). Could I use the CI engine model to represent the SI engine of my vehicle, or the two model are mutually exclusive meaning I can't use CI engine for the SI engine and viceversa?